Speckled Alder

Light Needs

Partial Shade to Full Sun

(At Least 3 Hours of Direct Sunlight)

Mature Height

12 - 15 Feet

Mature Spread

12 - 15 Feet

Growing Zones

3 to 8

Speckled Alder is a native on the east side of the Mississippi River and is common in areas with wet and sandy soils along streams and lakes. Alnus incana ssp. rugosa gets its common name from the white, raised lenticels on its dark-colored stems. This deciduous shrub has a glorious yellow fall color and brownish-colored catkins in spring that appear just before the leaves sprout. 

Speckled alder can be grown as a single-trunk tree or left to spread naturally by its underground suckers. Use its spreading to fill in large areas and form a windbreak or habitat for local wildlife. The leathery leaves support the caterpillars of the green comma butterfly, while other small animals and insects eat the bark, seeds, and wooly aphids that may attack this shrub. The wettest zones of a rain garden and along ponds or streams are ideal locations to plant speckled alder.

Speckled Alder Care

Speckled Alder prefers wet soil with an average or sandy texture. At least 6 hours of direct sun is preferred. This shrub is cold tolerant and grows well in USDA zones 3-6; however, it does not tolerate high heat and humidity south of zone 6. Speckled alder requires acidic soil and will show signs of chlorosis in a pH level above neutral (7.0). Fertilizing is not necessary. 

Pruning is only needed to control the spread and dense growth of speckled alder. Cut the oldest branches down to the base of the shrub in late winter, along with any dead, damaged, or diseased branches. Deadheading or thinning is not required when this shrub is grown to support wildlife habitat. Mulch the root zone annually with arborist chips or shredded leaves to improve moisture retention; this is especially beneficial for shrubs planted in drier locations of the garden. 

Speckled Alder Spacing

Speckled Adler can spread 12-15 feet, which means each shrub needs to be spaced 12 feet from the center of the next. You can plant the shrubs closer for quick cover; however, pruning will need to be done seasonally to ensure the area does not become overgrown.